The present invention relates to fibercane (Arundo donax L.) and to methods of propagating new plants. Arundo donax is a member of the Poaceae family and has several common names including xe2x80x9cgiant reedxe2x80x9d, xe2x80x9cSpanish canexe2x80x9d, xe2x80x9cgiant canexe2x80x9d, and xe2x80x9cfibercanexe2x80x9d. Arundo is a native of Mediterranean coastal areas where it is a robust perennial grass 3 to 10 meters (9 to 30 feet) tall, growing in many-stemmed cane-like clumps. Arundo spreads from horizontal rootstocks below the soil and often forms large colonies many meters across. Individual stems or culms are tough and hollow, divided by partitions at nodes like bamboo. Stems are from 1 to 4 centimeters in diameter. Culms are unbranched or with single (rarely multiple) lateral branches from nodes. The pale green to blue-green leaves broadly clasp the stem with a heart-shaped base or leaf sheath, about 2-6 cm wide at the base of the blade or lamina and tapering to the tip, up to 70 cm or more in length. Leaves are arranged alternately (not opposite each other) throughout the culm, very distinctly two-ranked (in a single plane).
Arundo produces a tall, plume-like flower-head at the upper tips of stems, the flowers closely packed in a cream to brown colored cluster borne from early spring to early fall, but these flowers do not produce viable seeds or achenes in North America. Culms may remain green throughout the year but often fade with semi-dormancy during the winter months or in drought. Arundo can be confused with cultivated bamboos and corn, and in earlier stages with some large-stature grasses, especially Phragmites (Common reed) which is less than 4 meters tall and has panicles which are less than 3 dm with long hairs between the florets. Fibercane is a perennial reed with stems which are erect and hollow. Three species of Arundo occur world-wide in tropical to warm temperate climates. Arundo donax is naturalized and invasive in many regions, including southern Africa, sub-tropical U. S. through Mexico, the Caribbean islands and South America, Pacific Islands, Australia and Southeast Asia as described in Tracy, J. L., and DeLoach, C. J., 1999. xe2x80x9cSuitability of Classical Biological Control for Giant Reed (Arundo donax) in the United States:xe2x80x9d In C. E. Bell (ed.) Arundo and Saltcedar: The Deadly Duo, Proceedings of the Arundo and Saltcedar Workshop, Jun. 17, 1998, Ontario, Canada, pp. 73-109, and these references are incorporated herein.
Being a typical xe2x80x98reedxe2x80x99, Arundo appreciates very moist soils and will often be found growing in water at the edge of coastal xe2x80x98slacksxe2x80x99. In its native habitat, the stems are persistent, becoming rather woody in their second year. Nodal side shoots or xe2x80x98keikisxe2x80x99 are formed along 2nd year stems and if these come into contact with the ground, will root giving rise to new plants some distance away from the parent, provided the culm is still attached to the parent plant.
Arundo is currently propagated by sections of rhizomes. The xe2x80x98keikisxe2x80x99 which readily form on second year stems also can be detached and placed in water. Rooting usually takes place within 2 or 3 weeks, after which, the young plants can be potted into 20 cm pots using a good quality compost.
The thick, woody rhizomes can also be divided in April/May before the new growths have grown too large. It is better to lift the entire rootstock and cut through the rhizomes using a very sharp knife or saw. Sections can be replanted and care should be taken to ensure that they do not dry out especially during the first few weeks.
Arundo plants in North America do not produce viable seed, and seedlings are not observed in the field. Population expansion occurs through vegetative reproduction, either from underground rhizome extension of a colony or from plant fragments carried downstream, primarily during floods, to become rooted and form new clones. Horticultural propagation in the greenhouse is routinely done by planting rhizomes which readily establish. Fresh stems form roots at nodes under laboratory conditions (T. Zimmerman and J. Bunn, unpub. data), and root formation does occur where an attached culm has fallen over and is in contact with the substrate.
New shoots arise from rhizomes in nearly any season, but are more common during spring. Growth likewise occurs in all seasons, but is highly sensitive to temperature and moisture. During warm months with ample water Arundo culms are reported to attain growth rates of 0.7 meters per week or about 4 inches per day, putting it among the fastest growing terrestrial plants. Biomass production has been estimated at 8.3 tons dry weight per acre as described in Perdue, R. E., 1958. xe2x80x9cArundo donaxxe2x80x94source of musical reeds and industrial cellulose.xe2x80x9d Econ. Botany, 12(4):368-404, and which is incorporated herein. Young stems rapidly achieve the diameter of mature canes with subsequent growth involving thickening of the walls. Age of individual culms is certainly more than one year and branching seems to represent stem growth in later years, while rhizomes show indeterminant growth. Branches also form when a stem is cut or laid over. Die-back is infrequently observed but culms fade or partially brown-out during winter, apparently becoming dormant under cold conditions. The outstanding growth trait of this plant is its extremely flexible ability to survive and grow at almost any time under a wide variety of environmental conditions.
Stems are used as measuring rods, walking sticks, fishing poles, musical instruments, reeds for woodwind instruments such as clarinets and saxophones, baskets and mats. Stems also serve as support for vines and similar climbing plants, and for making trellises and the like for climbing cultivated plants. The plant makes a good quality of paper, and in Italy the plant is used in the manufacture of rayon. Variegated and glaucous-leaved varieties are used as ornamentals. Because of rather high yields from natural stands, cane has been suggested for biomass for energy. As fodder, only the young leaves are browsed; the stems are woody, and the grass unpalatable in later stages.
Arundo donax does not produce viable seed. Current methods of propagating Arundo involve the labor intensive process of digging up the rhizome, cutting the rhizome into sections, and then planting the rhizome sections in the field. A simpler, less labor intensive method would improve the commercial production of Arundo.
In the method of the present invention, stems of fibercane are cut above ground and laid whole or in sections in shallow furrows or on level ground. The cut stems then may remain uncovered, or are covered either partially or entirely with soil. The stems are covered by hand or with machinery. Under optimal growing conditions nodal or axillary buds will develop into plants and initiate the production of rhizomes and new plants.
Definitions
In the description and tables which follow, a number of terms are used. In order to provide a clear and consistent understanding of the specification and claims, including the scope to be given such terms, the following definitions are provided:
Organic material(s) As used herein, the term xe2x80x98organic materialxe2x80x99 means carbon-based material having plant, microbial or animal origin. Examples of organic materials include mulch, peat, manure, moss, bark and sawdust.
Inorganic material(s) As used herein, the term xe2x80x98inorganic materialxe2x80x99 means any material that is not organic material, such as soil, limestone, ash, lime or industrial waste.
Furrow As used herein, the term xe2x80x98furrowxe2x80x99 means an extended indentation in the surface of the soil or planting medium.
Rhizome As used herein, the term xe2x80x98rhizomexe2x80x99 refers to an underground, modified, creeping stem which is solid and usually grows horizontal to the soil surface.
Node(s) As used herein, the term xe2x80x98nodexe2x80x99 refers to a joint or notch on the stem or culm at which point a leaf can be attached and above which a single nodal bud is present.
Seed cane As used herein, the term xe2x80x98seed canexe2x80x99 refers to whole stems or culms, or any portions thereof, which are used as planting material to generate new plants.
In the method of the present invention, stems of fibercane are cut above ground and laid whole or in sections in shallow furrows or on level ground. The stems then may remain uncovered, or can be covered partially or entirely with soil. The covering of the stems is done by hand or with machinery. Under optimal growing conditions nodal or axillary buds will develop into plants and initiate the production of rhizomes and new plants. In a preferred embodiment of the invention, the following conditions are met:
1) Seed cane having viable nodal buds, that may be dormant or starting to produce shoots, should be neither too old nor too young. In most environments, 6-9 months is usually the optimal age, but in frost-free environments, stems that are more than a year old will often result in successful establishment.
2) The seed cane should not be covered too deep in the soil; 5 cm or less is usually optimal. This can be done by hand or by machines such as sugarcane planters.
3) After planting, moisture needs to be supplied by adequate rainfall and/or supplemental irrigation.
4) Seed cane should be planted as soon as possible after harvesting, although it can be stored under cool, moist conditions for as long as several months.
There are numerous advantages of using the method of the present invention. Since Arundo donax does not produce viable seed, it currently is propagated commercially by using the buds on the underground rhizomes as propagules. The method of the present invention uses buds associated with the above-ground nodes on the stem or culm (seed cane) as propagules. The stems of Arundo are hollow, but the rhizomes are solid. Seed cane can be harvested by hand with hand tools, chainsaws or with other machinery such as sickle-bar mowers or disk mowers mounted on a tractor. Compared to harvesting underground rhizomes, much less time is required to harvest a given number of propagules using the method of the present invention. Also, the weight of seed cane per propagule is much less than the weight of rhizome per propagule, which makes physical handling of the propagules easier. Since seed cane is not contaminated with soil, as the rhizomes are, seed cane more easily meets phytosanitary regulations and will be easier and cheaper to import and export compared to rhizomes. Also, since harvesting seed cane does not disrupt the rhizomes underground, areas used for seed stock do not have to be replanted after harvesting seed cane and repeated generation of propagules is faster and cheaper for seed cane versus using rhizomes.